The winds on the Sierra's eastern front are known as powerful, tricky

Below:

Next story in Life

WASHINGTON — The crash that killed entrepreneur Steve Fossett, famed for his daredevil aerial feats, probably was caused by downdrafts that exceeded the ability of his small plane to recover before slamming into a California mountainside, federal safety officials said Thursday.

Fossett, 63, disappeared on Sept. 3, 2007, after taking off alone from a Nevada ranch owned by hotel magnate Barron Hilton for what was supposed to be a short pleasure flight. His Bellanca 8KCAB-180 — a single-engine, two-seater known as the "Super Decathlon" that was sometimes used for acrobatic flying — crashed near Mammoth Lakes, Calif.

An extensive, high-profile search failed to turn up any clues to his fate. A year later, on Oct. 7, 2008, a hiker found some of Fossett's belongings, including a pilot certificate and another identification card. An aerial search located the wreckage about a half-mile away at an elevation of about 10,000 feet.

At breakfast on the day of the accident, Fossett told the ranch's chief pilot that he intended to fly along Highway 395 and that he did not plan to wear a parachute, which would have been required for acrobatics, the National Transportation Safety Board said in a report.

Radar track initially dismissedThe radar track was initially dismissed in the search for Fossett because an employee at Hilton's ranch had reported seeing the Bellanca in a different location at about the time of the radar track, the report said. It was later determined that the employee's time estimate of the sighting was off by nearly an hour, the report said.

The radar track shows what is now believed to be Fossett's plane flying south along a crest of the Sierra Nevada Mountains. The track started about 35 miles south-southwest from where he took off that morning, continuing roughly parallel to Highway 395 about 10 miles to the west of the road.

The first few minutes of the track indicated an altitude of about 14,500 feet to 14,900 feet, while the rest of the track consisted of blips with no altitude or identifying information, the report said.

Based on its investigation — including weather reports, interviews with other pilots who flew in area that day and an examination of the wreckage — the board concluded the Bellanca was probably unable even at full power to climb out of what were likely powerful downdrafts.

A contributing factor, the report said, was a combination of high altitude and weather conditions that resulted in less dense air. The lighter air reduces an airplane's performance by exerting less force on the wings, reducing lift.

The wreckage examined by investigators was charred from a fire that erupted on impact and scattered over an area 350 feet long and 150 feet wide, the report said. The main wreckage was in a group of Ponderosa pines and the engine was about 100 feet away. Small planes do not carry the cockpit voice or data recorders required in airliners.

Fossett, who made a fortune in the Chicago commodities market, gained worldwide fame for setting records in high-tech balloons, gliders, jets and boats. In 2002, he became the first person to circle the world solo in a balloon.

Powerful and tricky windsWithin two days of Fossett's disappearance, experienced pilots were speculating that even the master of aerial adventure could have fallen victim to the notorious winds on the Sierra's eastern front that are so powerful and tricky they can swirl an airplane like a leaf and even shear off a wing.

"There's been times when I've been flying in the wind and my blood turns cold," Adam Mayberry, a private pilot and former spokesman for the Reno-Tahoe International Airport, said at the time.

Wind gusts in the area can whip up without warning from any direction, with sudden downdrafts that can drag a plane clear to the ground. Passengers flying even on commercial airliners between Las Vegas and Reno know to keep their seat belts fastened for a ride that is never smooth.

Mark Twain wrote about the "Washoe Zephyr" — named for the Nevada county — in the book "Roughing It."

"But, seriously, a Washoe wind is by no means a trifling matter. It blows flimsy houses down, lifts shingle roofs occasionally, rolls up tin ones like sheet music, now and then blows a stagecoach over and spills the passengers," he wrote.

Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.